The present invention relates to fuel rails and, more particularly, to fuel rail damping devices.
In modern internal combustion engines, fuel injection systems typically include a plurality of fuel injectors. A fuel rail supplies fuel to the fuel injectors. A typical fuel rail will include several sockets, within each of which is mounted a fuel injector. Thus, multiple fuel injectors typically share and are supplied with fuel by a common fuel rail. The injectors are sequentially actuated to deliver fuel from the fuel rail to the inlet port of a corresponding engine cylinder according to and in sequence with the operation of the engine. The sequential operation of the fuel injectors induce variations in pressure and pressure pulsations within the common fuel rail. The pressure pulsations within the fuel rail can result in undesirable conditions, such as fuel line hammer and maldistribution of fuel within the fuel rail.
U.S. Pat. No. 5,617,827, the disclosure of which is incorporated herein by reference, discloses a fuel rail that includes a conventional fuel rail damper. Conventional fuel rail dampers are typically formed from two thin stainless steel walls or shells, which are joined together in an air and liquid tight manner. Once joined together, the shells define a plenum therebetween. The material from which the shells or walls are constructed must be impervious to gasoline, and the shells must be hermetically sealed together. The shells or walls must have substantially flat sides that flex in response to rapid pressure fluctuations within the fuel rail. The flexing of the shells absorbs energy from the pressure pulsation to thereby reduce the speed of the pressure wave and the amplitude of the pressure pulsation/spike.
The two shells of a conventional fuel rail damper are typically sealed together through welding. More particularly, the two shells typically include a respective flange disposed generally around the periphery of the shells. The entire periphery of the flanges must then be welded together to thereby hermetically seal the shells together. The surface area that requires welding is therefore relatively substantial, and thus the welding operation is time consuming. A single imperfection in the welded periphery results in an plenum that is not properly sealed, and thus a defective fuel rail damper. Further, the welding operation causes a divergence of the flanges above or outside of the weld relative to the plenum, which potentially contributes to subsequent interferences between the damper and associated holders which orient and retain the damper in place within the fuel rail. Thus, at times, assembly of the damper into the fuel rail is rendered problematic. Moreover, the flanged shape of damper walls or shells that is needed to facilitate the welding operation reduces the effective surface area of the damper, and thus reduces the functional surface area thereof.
The shells or walls from which the fuel rail damper is constructed are typically flat stainless steel or metal pieces, which are then stamped to the proper shape and to form the flange. The faces of the shells or walls must be substantially flat, generally within approximately 0.5 mm. Most stamping processes are not capable of repeatedly and efficiently producing parts in conformance with such a flatness requirement, and thus waste and inefficiency result.
When exposed to sufficiently high pressure pulsations, the faces of the shells or walls approach their elastic or compliant limits and may contact each other or collapse. Due to the exposure to such high pressure pulsations, creases may form along the approximate center of the faces or shells. The creases may result in an eventual yielding of one or both of the shells. Further, such creases may facilitate the development of leaks and thereby destroy the function of the fuel rail damper.
Therefore, what is needed in the art is a fuel rail damper that does not require a weld around the entire periphery thereof in order to define and seal the plenum.
Furthermore, what is needed in the art is a fuel rail damper that is constructed in a manner that reduces susceptibility to leaks.
Still further, what is needed in the art is a fuel rail damper having increased functional surface relative to a conventional fuel rail damper for a given package size.
Even further, what is needed in the art is a fuel rail damper that is constructed in a manner that reduces interference with the fuel rail holders.
Moreover, what is needed in the art is a fuel rail damper that is constructed in a manner that eliminates the need to stamp the shells/faces thereof, and thus more repeatably conforms to the required flatness.
Lastly, what is needed in the art is a fuel rail damper that is less susceptible to degradation and/or failure when exposed to pressure levels higher that exceed the intended pressure range of operation.
The present invention provides a fuel rail damper.
The invention comprises, in one form thereof, a hollow member having a first end and a second end, opposing first and second sides, and a first face and a second face interconnecting and spacing apart the first and second sides. Each of the first and second ends are sealed in an air tight manner to thereby define a chamber in conjunction with the first and second sides and the first and second faces.
An advantage of the present invention is that only the ends of the fuel rail damper are sealed by welding, and thus substantially less area must be sealed by welding, thus saving time in the welding operation and reducing the susceptibility of the fuel rail damper to leaks due to a defect weld.
A still further advantage of the present invention is that functional surface area is increased relative to a conventional two-piece fuel rail damper of the same overall dimensions. Similarly, the same damping capabilities are achieved in a smaller package size. A further advantage is that the flatted ends resulting from the forming and welding operations can be shaped and used for mounting, locating and anti-rotation with respect to the fuel rail.
An even further advantage of the present invention is that potential interference with the fuel rail holders is reduced.
Yet further, an advantage of the present invention is that susceptibility to degradation and/or failure due to high-magnitude pressure pulsations is reduced.